Plate-clamp



Oct. 1931- c. G. PRITCHARD ET AL 1,327,300

PLATE CLAMP Fnd Sept. 22, 1928 5 Sheets-Sheet 1 I H ,u,

INVENTORS A 7 Car! GPrH'chard BY Charles WH rrold Oct, 13, 1931. c. G.PRITCHARD ET AL 7,

I PLATE CLAMP Filed Sept. 22, 1928 3 Sheets-Sheet 2 INVENTORS Carl G.Prhchard Charles W. 'Harrold ATTORNEY Oct. 13, 1931. c. G. PRITCHARD ETAL PLATE CLAMP Filed Sept. 22. 1928 5-Sheets-Sheet 5 FIG. 5.

A pun BY Charles W Harrold ATTORNEY CARL G. PRITCHARD, F HIRAM, ANDCHARLES W. HARROLD,

Patented Oct. 13, 1931 UNITED STATES :PATENT OFFICE 0F CLEVELAND, OHIO,

ASSIGNORS TO HARRIS-SEYBOLD-POTTER COMPANY, OF CLEVELAND, OHIO, A COR-TQRATION OF DELAWARE PLATE-CLAMP Application filed September 22, 1928.Serial No. 307,583.

Our invention relates to improved clamping mechanism for securingflexible sheets or plates in even and firm contact with a suitablesupport, such as a printing-press cylinder, and is particularly adaptedfor securing the zinc plates to the cylinders in oflset printingpresses, though it may be advantageously used in other types of presses.

The objects of our invention are, among other things, to provide asimple and novel clamp mechanism for such printing plates which shall beconvenient to operate and which shall strain and hold the plate Wrapped,

about the cylinder surface with a uniform tension in all directions soas to prevent any wrinkles or unevenness on the surface of the flexibleplate whereby accurate printing is ensured; also to provide a simplifieddevice to facilitate the shifting of the flexible printing plate forproperly positioning same and also to enable the plate to be readilyshifted in all directions without actually releasing same so as toproduce accurate adjustments.

A further object of our invention is to provide a plate-clampingmechanism of such a character that a small opening or gap in thecylinder willalford sufficient space for its 1 location and manipulationwhile permitting an almost continuous printin surface on the cylinderwhile diminishing the width of the gap when the plate is in stretchedprinting position.

A further feature of our invention is the provision of an improvedplate-clamp embodying the desired attributes of simplicity, elficiencyand durability, and which will enable the flexible plate not only to beclamped to the cylinders and easily and quickly loosened therefrom, butalso to be readily shifted or positioned transversely, longitudinallyand angularly on its supportin member with a reduction of the likelihoodo derangement or mutilation of the plates to a minimum in suchoperations in that the adjusting mechanism is conveniently locatedoutside the zone of'such printingplats wrapped about the cylinders.

With these and other objects in View, our invention comprises theconstruction, combination and arrangement of the various partly brokenaway to show our improved plate-clamp in a preferred form;

Fig. 2 is a longitudinal section taken on the line 22 of Fig. 1;

Fig. .3 is an enlarged transverse section taken on the line 3-3 of Fig.1;

Fig. 4. is an enlarged end view of part of the cylinder and associatedparts shown in Figs. 1 and 2;

. Figs. 5, 6 and 7 are. detailed perspective views of some of theclamping members shown in Figs. 1, 2 and 3;

Fig. 8 is a view like Fig. 1 showing a modified form of theplate-clamping mechanism;

Fig. 9' is an enlarged transverse section taken on the line 9-9 of Fig.8;

Fig. 10 is a fragmentary section of another modified form; and

Fig. 11 is a fragmentary end view partly in section showing a thirdmodified form of our plate-clamping mechanism.

Similar numerals refer throughout the several figures.

Referring more particularly to Figs. 1-7, the press cylinder 12 is ofthe customary hollow construction having the peripheral cylindricalside-walls 13 integral with the ends 1 1 each of which ends is providedwith the outwardly extending bosses 15 which serve to support thecylinder 12, in the press framework bearings (not shown). Extendinglongitudinally along the surface of the cylinder 12 is the T-shaped slot16 (Fig. 3) having the inwardly extending side flanges 17,- within whichslot the plate-clamping mechanism is located. Fastened to the cylinder12 by bolts 18 in the wider portion-of the slot 16 are twooppositely-disposed longitudinal guide-members 19, the outer surfaces ofwhich are co-exten'sive with the peripheral surface of the cylinder 12as shown in Fig. 3. Each guide-member 19 is provided with a flaringgroove 20 (Fig. 5) within which slide the cam-plates 21 (Fig. 6) havingthe lon ito similar parts v tudinal grooves 22 within which the slida le7 37 which are coincident with the peripheral 'the bottom edge ofcam-bars 23 (Fig. 7)l are located (Fig. 3). The plates 21 have t espaced-apart pins 24 riveted thereto and extending through the grooves22, and these pins 24 are adapted to be engaged by the equallyspaced-apart angular cam faces 25 integral with the cam-bars 23 as shownin Figs. 1 and 7. Each camplate 21 has the roundedupwardly-projecting-nose 26 opposite the groove 22 and adjacent theopening of the grooves 20 (Fig. 3), around which noses 26 the cylinderplate P is drawn when fastened to the cylinder 12.

Within the inner portion of the slot 16 and adjacent the flanges 17(Fig. 3) are arranged two oppositely-disposed plates 27 which areadapted to slide radially within the slot 16 and in contact with theflanges 17. The plates 27 are slightly longer than the cylinder 12 (Fig.2)., and have reduced end portions 28 which project alj rough openingsin the cylinder ends 14. 7 he plates 27 are also provided withoppositely-disposed longitudinal guide grooves 29 iii vihich slide theclamping bars 30. Each of the reduced ends 28 carries a downwardlyprojecting pin 31 around which is the coiled spring 32 which bears onthe openings 33 formed in the cylinder ends 14 and also bears on thereduced ends 28 as shown in Figs. 2 and 4.

Projecting outwardly from, and fastened to, the cylinder ends 14 are thebrackets 34 which partially enclose the ends 28 of the plates 27 (Fig.2), and each of these brackets 34 carries a pair of screw-threaded bolts35 the tips of which bear on the vertical surfaces of the reduced ends28 for end adjustment of the plates 27, while a pair ofvertically-disposed screw-bolts 36 passing through the brackets 34 coactwith the top surfaces of the plate ends 28 for radial ad ustment of theplates 27. Such bolts 35 and 36 being located outside the cylinder ends14 aflord convenient manipulating means for making both end and radialadjustments for the plates 27. The cylinder ends 14 also carry the ringssurface of the cylinder 12 when provided with the plate P (Figs. 1' and2) and each of these rings 37 is provided with a pair ofhorizontally-disposed screw-bolts 38 which bear on opposite ends of thecam-bars 23 to adjust the latter longitudinally of the cylinder 12. (Theends of the plate P are held to the clamping bars 30 by the clampingmembers 39 fastened to the bars 30 by the set-screws 40 as shown inFigs. 2 and 3.

"When the plate P is wrapped loosely in position about the cylinder 12and is held'in place by the clamping mechanism just described in thepreceding paragraph, such clamping-bars 30 may be adjusted to shift theplate P longitudinally on the cylinder 12 by operating the screw-bolts35. After the plate P has been properly adjusted longitudinally it maythen be stretched tight about the cylinder 12 by operating thescrew-bolts 36 which acts to push the plates 27 radially toward the axisof the cylinder 12 thereby carrying the two ends of the plate P withsuch plates 27 (Fig. 3), and compressing the springs 32 (Fig. 4).Further tightening of the plate may be attained by operating thescrew-bolts 38 which slide the cam-plates 21 toward each other therebystraining the plate P and partially closing the gap between the ends ofthe plate as shown by dotted lines in Fig. 3, whereby theplate-supporting surface of the cylinder 12 is advantageously increased.The coil springs 32 hearing on the ends 28 of the plates 27 will keepthe latter in a loose position when the screw-bolts 36 are loosened inthe brackets 34.

Referring to the modified form of our improved plate-clamping mechanismshown in Figs. 8 and 9, a pair of oppositely-disposed complementarycam-bars 41 and 42 are arranged with their angular faces abutting (Fig.8), and slide in the wide end of the T- shaped slot 16 to form expandingor contracting wedge members therein as they are adjusted screw-bolts 43passing through the two rings 37 fastened to the cylinder ends 14. T hetwo adjacent inside cam-bars 41 carry hardened steel rounded noses ofthe plate P are bent and travel (Fig. 9).

By operating the pairs of screw-bolts 43 the cam-bars 41 and 42 willtend to draw the plate P tighter diminish the width of the gap between.the bar-noses 45 as the cam-bars 41 and 42 are shifted on each other inopposite directions. A reverse movement of the cam bars 41 and 42 willrelax the tension on the plate P and so loosen same on the cylinder 12.

Fig. 10 shows another modified form of mechanism for clamping andstretching the cylinder plate P about the cylinder 12. In the upper wideportion of the T-slot 16 cut in the cylinder 12 are placed twooppositely-disposed guide members 46 fastened to the c linder 12 byscrews 47. These members 46 ave irregular inner sloping surfaces 48.which receive irregular shaped clamping bars 49 to which are fastenedthe ends of the cylinder plate P by clamping means 50. The clampmg-bars49 also have threaded apertures 51 which carry screw-bolts 52. Saidscrew-bolts 52 have their oppositely-disposed heads in contact with eachother and the opposite ends of the screw-bolts 52 contact with the.inner vertical wall'sof the guide members 46. It can be readilyunderstood that upon turning the screw-bolts 52 in certain directionsmotion is given to the clamping-bars 49 which results in eithertightening or loosening the cylinder plate P around the cylinder 12.

45 over which the ends on the cylinder 12 and also:

by pairs of horizontally-disposed Fig. 11 shows a third modified form ofcon- 16 in the cylinder casting is one-half as wide ing a gap,

as in Fig. 3. The means for clamping and adjusting right end of thecylinder plate P is the same as in Fig.3, but the other left end of thecylinder plate P with its clamping means 53 fits in an irregular slot orgroove 54 out in a shaft 55 which has hearings in the end portions 14 ofthe cylinder 12.

At the near end (in Fig. 11) the shaft 55 is squared to receive a wrenchor crankby which it may be rotated, thereby drawing that end of thecylinder plate P tighter on the cylinder 12. Also mounted on one end ofthe shaft 55 is a ratchet 56 coacting with a pawl 57 held in position bya fiat spring 58. The pawl 57 is so designed with a flat surface 59along its back that it may be swung out of engagement with ratchet 56and heldout of such engagement by the spring 58 hearing on the flatsurface 59.

In all the forms shown and described we have provided means forincreasing or diminishing the width of the slot 16 coincident with theprinting surface of the plate P without the necessity of changing theadjustment of the clamping members which hold the ends of such plate.When the plate P is tensioned the supporting area on the cylinder 12beneath the plate is thereby increased. Ourinvention is not to berestricted to the precise details of construction shown since variouschanges and modifications may be made therein without departing from thescope of the invention or sacrificing the advantages derived from itsuse.

We claim as our invention:

1. A plate-clamp for positioning a flexible plate on its supportcomprising clamping members to gripthe plate ends, complementary cammembers bearing on the plate ad acent the plate ends,an d means to slidesaid cam members on each other in both directions without moving saidclamping. members to tension and loosen said plate on said support.

2. A printing. cylinder having a gap,

clamping members within the gap to grip, the ends of a flexible platewrapped about the cylinder, complementary cam members bearingon theplate adjacent the plate ends to tension the plate on said cylinder, andmeans to slide said cam members on each other-1n both directions withoutmoving said;clamping members to tension and loosen sald plate .on saidcylinder.

3. In combination, a printing 0 linder having a gap, means for holding aexible plate thereto, a grooved plate bearing on the flexlble plateadjacent its end, a coacting cam bar extending longitudinally within thegrooved plate and adjusting screws coacting with the ends of said bar toshift said grooved plate for drawing the flexible plate tight on saidcylinder without moving said plate holding means. I r p 4-. Incombination, a printing cylinder'havend of means for holding a flexibleplate thereto, a grooved plate bearing on the flexible plate adjacentits end, a coacting cam bar extending longitudinally within the groovedplate and adjusting screws located outside the cylinder ends andcoacting with the ends of said bar to shift said grooved plate fordrawing the flexible plate tight on said cylinder without moving saidplate holding means.

5. A printing cylinder having a gap, clamping bars within the gap togrip the ends of a flexible plate wrapped about the cylinder,complementary cam-bars coacting with said plates, andoppositely-disposed coacting threaded members associated with said cambars for moving the latter edgewise in mutual kparallelism withoutmoving said clamping 6. A printing cylinder having a gap, clamping meanswithin the gap to hold the end of a flexible plate on the cylinder, saidmeans being movable angularly, longitudinally and transversely withrespect to said cylinder, and means for changing the width of saidcylinder gap without moving said clamping means or altering theadjustment thereof. I

7. A printing cylinder having a gap clamping means wlthin the gap tohold the end of a flexible plate on thecylinder, said means beingmovable angularly, longitudinally and transversely with respect to saidcylinder, and means bearing on said plate adjacent the plate ends forchanging the width of said cylinder gap without moving said clampingmeans or altering the adjustment theregf. I

8. printing cy inder having a gap, clamping means within the gap to holdthe a flexible plate on the cylinder, said means being movableangularly, longitudinally and transversely with respect to saidcylinder, and means for tensioning theplate independently of saidclamping means without moving same. i

9. A printing cylinder havinga gap means within the gap for holding theends of a flexible plate wrapped about the cylinder, and other meanswithin the cylinder bearing on the plate adjacent its ends with agradually increasing. pressure to increase the plate-supporting area ofthe cylinder beneath the late adjacent the gap without changing the endin the plate or moving said plate-holding means.

'10. A printing cylinder having a means within the gap for holding theof a flexible plate der, and other means within the cylinder bearing onthe plate adjacent its ends with a gradually increasing pressure toincrease the plate-supporting area of the cylinder beneath the. plateadjacent the ap and also tighten the latter on the cylindger withoutchanging g, en 5 wrapped about the cylinthe'bend in the plate or movingsaid plateholding means.

- 11. A printing cylinder having a gap, means Within the gap for holdingthe ends of a flexible plate wrapped about the cylinder, means forshifting said holding means to register the plate on the cylinder, andother means within the cylinder bearing on the plate adjacent its endswith a gradually increasing pressure to increase the plate-supportingarea of the cylinder beneath the plate adjacent the gap without changingthe bend in the plate or moving said plate-holding means.

12. A plate-clamp for positioning a flexible plate on its supportcomprising means for holding the plate ends in position andpositivelyactuated means bearing along the supported line of the platebetween said support and holding means to increase the supported area ofthe plate while drawing same tight on said support without changing thebend in, or moving said holding means secured to, said plate ends.

13. A printing cylinder having a gap, clamping bars within the gap togrip the ends of a flexible plate wrapped about the cylinder,complementary cam-bars having projecting noses bearing on the plateadjacent the plate ends, and oppositely-disposed, coacting threadedmembers associated with said cam-bars for moving the latter edgewise inmutual parallelism without moving said clamping bars.

14. A plate-clamp for positioning a flexible plate on its supportcomprising clamping members to grip the plate ends, positively-actuatedexpansible cam members having projecting noses bearing on the plateadjacent the plate ends while drawing same tight to increase thesupported area of the plate on said support without moving said clampingmembers secured to said plate.

15. A printing cylinder having a gap, clamping members within the gap togrip the ends of a flexible plate wrapped about the cylinder, andpositively-actuated expansible cam members having projecting nosesbearing on the plate adjacent the plate ends while drawing same tight toincrease the supported area of the plate on said cylinder without movingsaid clamping members.

CARL Gr. PRITCHARD. CHARLES W. HARRQNLD.

